There are several taxonomic systems available for identifying Fusarium species. The philosophy used in each taxonomic system is discussed as well as problems encountered in working with Fusarium species in culture. Fusarium species are toxigenic, and the mycotoxins produced by these organisms are often associated with animal and human diseases. The implications for the association of the carcinogens, fumonisins, produced by Fusarium moniliforme and other Fusarium species with human diseases are discussed. Foreign-body-associated fusarial infection such as keratitis in contact lens wearers, onychomycosis, skin infections, and disseminated multiorgan infections are discussed. Disseminated fusarial hyalohyphomycosis has emerged as a significant, usually fatal infection in the immunocompromised host. Successful outcome is determined by the degree of immunosuppression, the extent of the infection, and the presence of a removable focus such as an indwelling central venous catheter. These infections may be clinically suspected on the basis of a constellation of clinical and laboratory findings, which should lead to prompt therapy, probably with one of the newer antifungal agents. Perhaps the use of such agents or the use of colony-stimulating factors may improve the outcome of this devastating infection. However, until new approaches for treatment develop, effective preventive measures are urgently needed.

Taxonomy, biology, and clinical aspects of Fusarium species.

Effects of previous crop residues and tillage practices on Fusarium head blight (FHB) of wheat were examined. Fusarium head blight was monitored in plots of the FHB-susceptible spring wheat cultivar Norm following crops of corn, wheat, and soybeans in 1995, 1996, and 1997. Moldboard plow, chisel plow, and no-till treatments were imposed perpendicular to crop strips to establish a range of residue levels in each of the previous crop residues. Fusarium head blight incidence and severity were greatest when wheat followed corn and least when wheat followed soybeans. Incidence and severity were lower in moldboard plowed plots than in either chisel plowed or no-till plots, although differences among chisel plow and no-till treatments were not apparent. Yields of wheat were approximately 15% lower in plots where wheat followed corn or wheat than in wheat following soybeans and were 10% greater in moldboard plowed plots than in either chisel plowed or no-till treatments. The deoxynivalenol (DON) content of harvested grain was significantly correlated with FHB incidence and severity. The DON level in wheat following soybeans, averaged across tillage treatments, was 25% lower than in wheat following wheat and 50% of the level in wheat following corn. These findings suggest that changes in regional tillage practices, principally the move toward conservation tillage and reduced-till systems, contributed to the recent FHB epidemics in the Upper Midwest. Because differences in the type and quantity of crop residues in small plots affected disease development, it is likely that local sources of inoculum, such as those within a grower's field, contribute directly to the inoculum load and disease potential. The implication of these findings is that selection of cultural practices aimed to reduce inoculum-borne residues will assist in the control of FHB.

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PDIS.2000.84.1.71

The effect of previous crop residues and tillage on fusarium head blight of wheat

Fusarium oxysporum is an anamorphic species that includes both pathogenic and nonpathogenic strains. Plant pathogenic forms cause a wilt disease and are grouped into formae speciales based on their host range; some are further subdivided into pathogenic races. Many formae speciales are comprised of multiple clonal lineages and, in some cases, a pathogenic race is associated with more than one clonal lineage, suggesting independent origins. Although some evidence suggests one pathogenic race may give rise to another, recent derivation of a pathogen from a nonpathogen has not been documented. Most new occurrences of Fusarium wilt appear to be the result of a recent introduction rather than an independent local origin of the pathotype. Asexual propagation is the dominant influence on population structure in F. oxysporumand the absence of sexual reproduction is not likely to prevent this pathogen from continuing to inflict significant damage on susceptible crop hosts.

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The evolutionary biology of fusarium oxysporum

Nitrogen form and plant disease.

Changes in peroxidase and polyphenol oxidase activities in susceptible and resistant wheat heads inoculated with Fusarium graminearum and induced resistance

Quantitative estimations by plate counts of propagules of the bean root rot Fusarium in field soils

In soils of the Salinas watershed Fusarium solani and Fusarium tricinctum were found only in the cultivated soils. Propagules of Fusarium oxysporum were numerous and varied in the cultivated fields...

Shirley M. Nash

Papers

Quantitative estimations by plate counts of propagules of the bean root rot Fusarium in field soils

Quantitative and qualitative comparisons of fusarium populations in cultivated fields and noncultivated parent soils